The invention is directed to a pharmaceutical composition comprising a PEG-ASNase compound or a pharmaceutically acceptable salt thereof, and optionally at least one compound selected from the group consisting of protease inhibitor compounds, ribonucleotide reductase inhibitor compounds and HIV reverse transcriptase inhibitor compounds, and a pharmaceutically acceptable carrier. The invention is also directed to a method of inhibiting or treating Human Immunodeficiency Virus (HIV) infection, comprising administering to a patient in need thereof a therapeutically effective amount of a PEG-ASNase compound or a pharmaceutically acceptable salt thereof, and optionally at least one compound selected from the group consisting of protease inhibitor compounds, ribonucleotide reductase inhibitor compounds and HIV reverse transcriptase inhibitor compounds, or a pharmaceutically acceptable salt thereof.
The human immunodeficiency virus (HIV) is a retrovirus and is the agent of the complex disease that includes progressive destruction of the immune system (acquired immune deficiency syndrome; AIDS) and degeneration of the central and peripheral nervous system. This retrovirus is previously known as LAV, HTLV-III, or ARV. There have been various therapies to treat HIV infection, including therapies with combination drug regimens. Protease inhibitor compounds in combination with reverse transcriptase (RT) inhibitor compounds have shown success both in vitro and in vivo in patients infected with the virus. Protease inhibitor compounds interfere with the production of new infectious virus. A common feature of the HIV retrovirus replication is extensive post-translational processing of precursor poly-proteins by a virally encoded protease to generate mature viral proteins required for virus assembly and function. Inhibition of this processing prevents the production of new infectious virus.
Inhibition of the HIV protease by protease inhibitors may prevent proviral integration of infected T-lymphocytes during the early phase of the HIV-1 life cycle, as well as inhibit viral proteolytic processing during its late stage. HIV protease inhibitors have been extensively reviewed (A. Tomasselli et al., Chimica Oggi, 6-27 20 (1991) and T. Meek, J. Enzyme Inhibition 6: 65-98 (19.92). Retroviral replication routinely features post-translational processing of polyproteins. This processing is accomplished by virally encoded HIV protease enzymes. This post-translational process yields mature polypeptides that will subsequently aid in the formation and function of infectious viruses. If this molecular processing is inhibited, then the normal production of HIV is terminated. Therefore, it has been discovered that inhibitors of HIV protease may function as anti-HIV viral agents.
Retroviruses are widely distributed in vertebrates and are known to cause a variety of diseases in man and animals including HIV, leukemias and lymphomas. The entire retrovirus family is characterized by the presence of a unique enzyme, reverse transcriptase (RT), which transcribes the viral genomic RNA into a double-stranded DNA copy. Therefore, considerable efforts are being directed toward the control of HIV by means of inhibition of HIV-reverse transcriptase, required for replication of the virus. (V. Merluzzi et al., xe2x80x9cInhibition of the HIV-1 Replication by a Nonnucleoside Reverse Transcriptase Inhibitorxe2x80x9d, Science, 25, 1411 (1990)). For example, a currently used therapeutic compound, AZT, is an inhibitor of the viral reverse transcriptase (U.S. Pat. No. 4,724,232). Unfortunately, many of these compounds suffer from toxicity problems, lack of bioavailability or are short lived in vivo, viral resistance, or combinations thereof.
It is also known that the inhibition of HIV-reverse transcriptase (HIV-RT) by nucleoside analogue drug combinations indicate that they cannot alone inhibit the RT function completely, but instead can lead to the emergence of drug resistant viral strain. These strains of escape mutants repopulate and render nucleoside analogue therapy ineffective. The addition of protease inhibitor compounds to known nucleoside analogue combination therapies has helped to reduce the viral burden for a prolonged period of time.
Ribonucleotide reductase is an allosterically regulated enzyme that converts the nucleoside diphosphates to their corresponding deoxynucleoside diphosphates through a complex regulatory mechanism involving one or several electron transfer pathways. (Holmgren A. Hydrogen donor system for E. Coli Ribonucleoside diphosphate reductase dependent upon glutathione, Proc. Natl. Acad. Sci. USA, 1976, 73, 2275-9; Therlander L., Reductase of Ribonucleotides, Ann. Rev. Biochem. 1979,46, 133-58; Ashley G W, Stubbe J., Current ideas on the chemical mechanism of ribonucleotide reductase, Pharmac. Ther. 1985, 30, 301-29; Stubbe J., Ribonucleotide Reductase: Amazing and confusing, J. Biol. Chem. 1990, 265, 5329-32.) Reduction of the ribonucleotide by ribonucleotide reductase enables the DNA ploymerases to utilize the deoxyribonucleotides (dNTPs) during the process of DNA replication. Ribonucleotide reductase activity is well coordinated to the process of cellular proliferation and is markedly increased in the late G1 and the early S-Phase when the bulk of DNA synthesis occurs. (Corey J. G., Whitford Jr. T. W., Ribonucleotide reductase and DNA synthesis in Ehrlich ascites tumor cancer cells, Cancer Res., 1972, 32, 1301-6; Hammerstan E, Reichard P., Saluste E., Pyrimidine nucleosides as precursors of pyrimidines in polynucleotides, J. Biol. Chem., 1950, 183, 105-109.) The important role of ribonucleotide reductase in the synthesis of DNA makes it a target for chemotherapeutic agents. There has recently been found a class of 2-hydroxy-1H-isoindole-1,3-dione (HISID) which have been shown to have ribonucleotide reductase inhibitor activity (Nandy P, Lien E J, Avramis V I, Acta Oncologica, 33, 8, 953-61, 1994; Nandy P, Lien E J, Avramis V I, Rec Adv Chemoth 1:995-996, 1994; Nandy P, Lien E J, Avramis V I, Med. Chem. Res. 1995, 5:664-679.)
PEG-asparaginase (the polyethylene glycosylated form of E.coli-ASP) has been shown to be useful as a chemotherapeutic agent. In particular, PEG-asparaginase has been found to be an alternative preparation with a longer circulating half-life than E.coli L-asparaginase and has been useful in multiagent chemotherapy for childhood acute lymphoblastic leukemia. (Ettinger L J, Ettinger A G, Avramis V I, Gaynon P S, BioDrugs, 7, 1, 30-39, 1997). Also, PEG-ASNase may increase the anti-leukemic effect in isolated CNS relapse. (Malgolowkin M, Ortega S, Carcich D A, Steele D, Tischer D, Franklin J, Nandy P, Periclou A, Cohen L J, Avramis V I, Proceedings of ASCO, 17, 1998.)
PEG-ASNase is a conjugate of asparaginase with polyethylene glycol. This conjugation occurs through pegylation, a process in which polypeptides, such as enzymes and hormones, are coupled to polyethylene glycol so as to produce a physiologically active non-immunogenic water-soluble polypeptide composition. The polyethylene glycol protects the polypeptide from loss of activity and the composition can be injected into the mammalian circulatory system with substantially no immunogenic response. The process of pegylation is described in detail in U.S. Pat. No. 4,179,337, entitled xe2x80x9cNon-immunogenic Polypeptidexe2x80x9d, filed Jul. 28, 1977 and issued Dec. 18, 1979, which is incorporated by reference in its entirety herein. Covalent attachment of the polymer to the peptide is affected often by reacting PEG-succinimide derivatives with amino groups on the exterior of protein molecules. Other methods are also disclosed in U.S. Pat. No. 4,179,337, in Pollack et al., JACS, 298, 289 (1976), U.S. Pat. No. 4,847,325 and elsewhere in the art.
Applicants have discovered that PEG-asparaginase (PEG-ASNase) effectively works alone and synergistically works in combination with one or more of the following: protease inhibitor compounds, HIV reverse transcriptase inhibitor compounds, or ribonucleotide reductase inhibitor compounds, to treat infection by HIV.
Accordingly, in its principle aspect, this invention is directed to a pharmaceutical composition comprising a PEG-ASNase compound and optionally at least one compound selected from the group consisting of: protease inhibitor compounds, ribonucleotide reductase inhibitor compounds and HIV reverse transcriptase inhibitor compounds, and a pharmaceutically acceptable carrier. The invention is also directed to a method of inhibiting or treating Human Immunodeficiency Virus (HIV) infection, comprising administering to a patient in need thereof a therapeutically effective amount of a PEG-ASNase compound or a pharmaceutically acceptable salt thereof, and optionally at least one compound selected from the group consisting of protease inhibitor compounds, ribonucleotide reductase inhibitor compounds and HIV reverse transcriptase inhibitor compounds, or a pharmaceutically acceptable salt thereof.